The paper presents a proposed scheme for fast braking of induction motor drive system. The proposed braking strategy is based on the injection of an AC voltage to the rotor winding from three-phase SVPWM inverter during braking. The injected voltage must have the same frequency, same phase shift and opposite in direction to the rotor induced voltage. The purpose of this method is to reduce the rot...
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This paper deals with channel coding and carrier recovery design for high-speed adaptive modulation microwave radio transmission sytems. The challenges posed by the microwave channel are discussed and the design trade-offs are analyzed. The proposed flexible adaptive modulation solution employs M-QAM modulations from 4 QAM up to 512 QAM and a high rate LDPC code. The code-rate flexible LDPC code p...
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We study an unbiased finite impulse response (FIR) filter in applications to discrete-time state space models with polynomial representation of the states. The unique l-degree polynomial FIR filter gain and the estimate variance are found for a general case. The noise power gain (NG) is derived for white Gaussian noises in the model and in the measurement. The filter does not involve any knowledge...
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In the paper is proposed a load angle estimation method for synchronous generators. The estimation method is based on synchronous generator corresponding voltage-current vector diagram and parameters of generator, transformer and transmission lines. In addition measurement of the load angle is presented. The estimation results were compared with the measured ones. The estimation method gives satis...
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Ferroelectric ceramic materials have a wide range of applications because of their piezoelectric and pyroelectric properties. One of their most important physical properties is the specific heat. In this study, the specific heats of a series of lead-zirconate-titanate (PZT) compositions in the vicinity of the morphotropic phase boundary (MPB) were measured. The temperature range was from 1.8 to 30...
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This paper presents an experimental study on examining the effects of facial and racial features on gender classification. In order to show which facial feature is the most influential for gender classification, parts of several face images, such as, forehead, eyebrows, eyes, nose, lip and chin were masked. For dimension reduction, Principal Component Analysis (PCA) and for determination of gender...
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This paper presents a procedure for mathematical modelling of ring electric power systems for simulation of both transient and steady-state conditions. The idea of this procedure has been based on nodal voltages technique and on differentiation of Kirchhoff's current law (KCL) applied to each non-reference node of the system, the result of which a system of algebraic equations for nodal voltages h...
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This paper addresses the problem of electromechanical wave propagation in power systems. To mitigate this type of disturbance, this paper proposes a remote control strategy that could be applied to power system stabilizers. This strategy is based on wide-area measurements, and exploits the disturbance propagation speed to introduce an extra damping torque simultaneously with the disturbance arriva...
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A model for image and data pre-processing and communication between a dedicated PC and a PLC with Neural Network (NN) application is proposed in this paper. The proposed model defines guidelines for creating a multithreaded application for receiving real-time data from several digital cameras, parallel image pre-processing based on predefined user algorithms, calculation of input data vector for N...
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Robots, as complex systems, must detect and isolate faults with high probabilities while doing their tasks with humans or other robots with high precision and they should tolerate the fault with the controller. This necessity forced researchers to design various fault detection and isolation (FDI) for robot manipulators, mobile robots and mobile manipulators. In addition to FDI, a scheme should ap...
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The large amount of bandwidth and other resources required to deliver streaming media limits the number of concurrent users. We propose a virtual active network (VAN) architecture for streaming media data delivery over wide area networks. In the proposed architecture, cooperating proxies support multiplexing and delivery of live streaming media. The hierarchical delivery structure is dynamically a...
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Solar global irradiance received at a horizontal level on the earth varies significantly over short intervals due to diffuse radiation changes. Experimental data on global irradiance profiles received by fast data recording systems show that the global irradiance may be enhanced for a few minute periods by as much as 40%. The diffuse radiation is intensified by dry air mass formations, airborne na...
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Medium Access Control (MAC) protocols for WDM Ethernet passive optical networks (WDM-EPONs) suffer from low performance when the users' round trip times are different. In this paper a new MAC protocol for WDM-EPONs is introduced which overcomes the above limitation by filling the gaps in the scheduling program. Moreover, the proposed scheme favors the requests that present a burst-like behavior, b...
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The combination of RTS/CTS and EIFS enhancements has not adequately addressed the hidden terminal problem (HTP) in the receiver neighbourhood. The EIFS scheme protects ACK packets, while DATA packets are not shielded as the EIFS expires before they are delivered. Our proposed scheme is designed to address the shortcomings of the EIFS in protecting data packets. We propose a scheme which implements...
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A study on the impact of the phase errors distribution on the performances of the phased array systems has been produced using a complete and behavioral model for radiation-pattern characteristics . The study has shown how the phase errors distribution actually affects the performances demonstrating that the rms phase error is a valuable figure of merit of phased array systems but it is not suffic...
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In the area of EMC performance of electric motor drives, research is mainly focused on the EMC performance of inverter based drives. However, in most instances the soft starter is still an appropriate choice for motor control especially when accurate speed control of the load is not a specific requirement. The EMI generation of these converters has not been given the required importance, with only...
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Robot learning by imitation has become a key topic in robotics research in the last years, due to the increasing interest in social robots. While several architectures that deal with this topic have been proposed, few efforts have been done in finding unified formats that may help in analyzing and comparing these architectures. This paper firstly proposes a set of components that can be identified...
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In this article the reasons of occurrence of extralegal interruptions and issues related to updating of algorithms of their elimination in wireless WiMAX broadband networks are considered.
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There exist various techniques to extend reinforcement learning algorithms, e.g., eligibility traces and planning. In this paper, an approach is proposed, which combines several extension techniques, such as using eligibility-like traces, using approximators as value functions and exploiting the model of the environment. The obtained method, `Undelayed n-step TD prediction' (TD-P), has produced co...
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Wind Tunnel Test results of a real time optimization of a morphing wing in wind tunnel for delaying the transition towards the trailing edge are presented. A morphing rectangular finite aspect ratio wing, having a reference airfoil cross-section, was considered with its upper surface made of a flexible composite material and instrumented with Kulite pressure sensors, and two smart memory alloys ac...
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Split drivetrain configurations with multiple generators are one of the solutions for increasing the reliability and reducing the cost of wind turbines. The split drivetrain technology gives the ability to introduce multiple generators and by that reduces the gear size and facilitates variable-speed operation. This paper proposes a double input AC/AC nine-switch converter for direct conversion of ...
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